The invention relates generally to the field of rotary direction sensors and more particularly to the use of such sensors for controlling the creation of spark ignitions in the ignition system of an internal combustion engine.
For internal combustion engines, sensors are generally used to produce a spark timing signal which causes cylinder ignitions to occur at predetermined positions of the cylinder compression cycle. These sensors are normally either photosensitive devices, magnetic pick-up devices, Hall sensors or simple contacts which generally sense the rotational position of a rotary body which is synchronously rotated by the crankshaft of the engine.
Previous engine ignition systems generated spark timing signals solely in response to the rotational position of the rotary body and these systems did not prevent the generation of a spark ignition if the engine happened to be running in a reverse direction. Such a condition can easily occur in the two, three and four cylinder engines which are commonly used for marine outboard motors (two cycle engines). The occurrence of an ignition spark while the engine is rotating in a reverse mode can result in damage to the engine and carburetor. In addition, the general performance of an engine running in the reverse direction will be unsatisfactory. Therefore the prevention of spark ignitions when the engine is rotating in a reverse direction is a desirable result which the previous engine ignition systems have not produced. Previous systems have disregarded the problem and provided no apparatus for sensing the rotary direction of the rotating body which produces the ignition spark timing signals.